Lubricating oil



Patented Jan. 9, 1945 ES PATENT OFFlCE Lonarca'rmc on Charles C. Towne,Beacon, N. Ya assignor, by mesne assignments',-to The Texas Company,NewyYork, N. Y., acorporation of Delaware No Drawing. Application March8, 1941,

' Serial No. 382,335

20 Claims. (c1. 252-33) This invention relates to a lubricating oil, andparticularly to a motor oil adapted for the lubrication of bearings andcylinders of an internal combustion engine, such as a Diesel engineadapted for heavy duty service in tractors, buses and the like Thisapplication is a continuation-in-part of my copending application SerialNo. 267,918, filed April 14, 1939.

It is an object of the present invention to provide an improvedlubricating oil of this character which is not only effective to reducering sticking and engine wear, and minimize bearing corrosion in heavyduty service'of this character, but is also efiective to preventaccumulation ofduty Diesel tractor service is thereby obtained.

' In the copending application of Frank W. Hall and CharlesC. Towne,Serial No. 223,487, filed August 6, 1938, now issued as Patent No.2,257,601 of September 30,- 1941, there is disclosed and claimed theaddition'of a lubricating oil of the character of'a motor oil of a smallproportion of a phosphatide, such as lecithin, to reduce or inhibitlacquer formation and bearing corrosion. While such an oilis highlyeffective for the purposes intended, it-is found that when it is usedasa crank case lubricant in long time heavy duty service, such as. in aDiesel tractorlubricant,

unexpected because the metallic naphthenates heretofore suggested forthis purpose, such as aluminum naphthenate, uniformly increased the rateof bearing corrosion and have also seriously impaired the oxidation andcolor stability of the oil. The stannous naphthenate is prepared frompartially purified naphthenic acids obtained from petroleum, such as thenaphthenic; acids of lower molecular weight obtainable from a petroleumgas oil fraction, or the heavier naphthenic acids of higher molecularweight which are obtained ring sticking may occur. in a comparativelyshort and color change of the oil. Thisis all the more, 05-

from heavy residual mineral lubricating oil. The naphthenic acids may behighly purified although those which are partially purified by ,methodsconventional in the industry such that they have a neutralization numberof the order of 100-150 and containing a substantial proportion ofnonsaponifiable matter, are satisfactory. These acids are neutralizedwith a caustic soda solution to form sodium naphthenate; and to thesolution is then added a stannous salt, such as stannous chloride, insolid form to eflect a double decomposition with precipitation ofinsoluble stannous naphthenate. A water-immiscible organic solvent, suchas naphtha or benzol, is added which dissolves the stannous naphthenate;and the mix is allowed to; stand and stratify into a waterlayercontaining water-soluble salts and. a solvent layer containing thedissolved stannous naphthenate. {The layers are then separated, thesolvent layer washed several times with water to remove remainingwater-soluble salts, and the solvent layer then filtered through aninactive clay toremove suspended matter. The solvent is then stripped byheating to a distillation temperature to recover the stannousnaphthenate directly; or, the solvent layer may be mixed with a quantityo1 mineral lubricating. oil priorto or after filtration, and beforestripping, and then the solvent, stripped -ofl to obtain a lubricatingoil concentrate of stannous naphthenate.

The stannous naphthenate composition obtained is found to have aneutralization number varying between about to 90, and has a proportionof the order of 15-25% of non-saponiflable matter originally containedin the partially purified naphthenic acids. This composition isdissolved in the mineral lubricating oil adapted to be usedas the motoroil in a proportion to give a stannous naphthenate solid content ,ofabout 0.1-2.0% by weight. A preferred proportion range for 9. Diesellubricating oil is about 05-15% by weight.

The phcsphatides, or the leclthins as they are frequently called. whichare employed herein.

belong to the class of compounds having the general formula:

/H cmor =o where R and R are similar or dissimilar fatty acid radicalssuch as those derived from stearic, palmitic, oleic acids, etc., andwhere X represents an amino alcohol group. In thecase of lecithin,

X or the amino alcohol group is choline crncmmcmnon and in the case ofcephalin X is colamine .CHzCI-IaNI-I:

Other types of compounds falling within the class of phosphatides can beemployed, such-as sphengomyelin. Also metal derivatives or salts of thelecithins canbe employed. For example, the free erably a bleachedcommercial soybean lecithin is used, such as theproduct soldcommercially as Coloidol BT- which is commercial soybean lecithinbleached with hydrogen peroxide and'di benzoyl peroxide, or the productsold commercially as Coloidol HX which is commercial soybean"lecithinbleached with hydrogen peroxide. If desired, the commercialsoybean lecithin can be purified by extracting the soybeanoilwithacetone to obtain the product consisting'essentially of lecithin andcephalin. Also, the cephalin constituent can be separated from thelecithin by alcohol extraction, and either the purified lecithin orpurified cephalin or mixtures of the two in any desired proportion maybe employed for purposes of the present invention. Likewise,phosphatides derived from other sources, such as from the brainsandspinal column of cattle and from egg yolk, may be employed. Whereverthe expression phosphatide compound" is used throughout the descriptionand claims, it is to be understood that this includes any of th purifiedcompounds or derivatives thereof falling within this group, as well asany of the'comparativ'ely impure mixtures such as the commercial gradesmentioned above.

The phosphatide compound-is added to the motor oil in a proportion rangeof about 01-20% by weightyj'and in combination with the abovementionedproportionrange of stannous naphthenate a proportion of about 0.1-0.5%of lecithin is preferred for a Diesel lubricant. A very satisfactorymethod for adding the phosphatide com pound to t'he mineral lubricatingoil is to first form a concentrate, such as about a 50% solution of thelecithin or other phosphatide compound in a mineral lubricating oilwithin the motor oil visccsity range, and then add the concentrate tothe mineral lubricating oil in an amount suflicient to give the desiredpercentage of phosphatide compound therein. Preferably, a concentrate ofboth the phosphatide and the 'stannous naphthenate in A preferred theengine over extended periods of time.

type bearings than any otheroil heretofore known lubricating oil, suchas a mineral lubricating oil solution containing about 25% by weight ofeach of the above-named constituents, is prepared, and then added to thebulk of the mineral lubricating oil.

The modern development of internal combustionengines with extremelysmall clearances between piston and cylinder wall, has given rise to theproblem of so-called varnish or lacquer formation. This lacquergenerally appears as a yellowish or reddish brown him which depositsupon the metal surfaces, piston skirt, piston pin relief surface,cylinder wall,-,etc., during operation of Further, the moderndevelopment of the new type bearings, including connecting rod and mainbearings, which has involved a departure from the old babbit bearings,and introduced new alloyed bearings of the type of cadmium-silver,copperlead, etc., has accentuated the problem of bearing corrosion.These problems are particularly accentuated in connection with enginesadapted for heavy duty service, such as in Diesel tractor work. Leadingmanufacturers of Diesel engines and Diesel driven tractors haverecognized these'problems to be so serious that only special compoundedmineral lubricating oil specifically designed for crank case lubricationin such service and used for this purpose. Briefly, the Caterpillarendurance test is carried out in a single cylinder Diesel engineoperating at 900 RIP. M. with a water jacket temperature of 1'75" F;running continuously for 1000 hours or until rings are stuck asindicated in the increase in blowby, and in which the crank case oil isdrained every sixty hours and fresh oil supplied thereto. v

. For purposes of 9. Diesel engine lubricant, preferably a naphthenebase or coastal distillate lubricating oil of the proper viscosity rangeis selected. The oils are mad up into various grades of progressivelyincreasing viscosity, similar. to the motor oil grades S. A. E. 10 to S.A. E. 60.. By wayof example, a Diesel lubricating oilof S. A. E. 20grade was prepared by warming a straight naphtheme-base distillatehaving aviscosity of about 300 at F. to a temperature'of about then astannous naphthenate composition was added and the mix stirredmechanically-at this temperature until complete solution was obtained sothat the oil contained about 0.5% by weight of the starinousnaphthenate. A 50% concentrate of lecithin in mineral lubricating oilwas then added and stirred mechanically at a temperature not over 150 F.until ahomogeneous solution was obtained and to provide a proportion of0.5% by weight of lecithin in th oil. Asimilar Diesel lubricant of S. A.E. 30 grade was prepared in the same manner to contain 0.5% stannousnaphthenate and 0.5% lecithin, the base oil in this case being made upof 90% of a naphthene-base lubricating oilof a viscosityof about 750at-l00'F. and 10% of a naphthene-base oil of a viscosity ofabou-ti300at10.0 F. v.'.lypicali ;ests on theresult ing -oils'were asfollows:

' S. A..E. 20 S. A..E, 30 Term Diesel oil Diesel oil Gravity ..A. P 1 F-20.1 19. 4 ash; 380 390 Fire 25 446 S. U. viscosity at 100 F 323 S. U.viscosity at 130 F 139 252 S. U. viscosity at 210 F. 48 69Color-Lovibond 18045" 20%" Pour F 20 5 Carbon residue per centw 0. 16 0.19 Neutralization numbe 0.66 0. 71 Ash 0.12 0.11

The resulting compounded Oils were found to be of satisfactory odor,entirely color stable and to have satisfactory. storage stability. I

In place of the s'tannous naphthenate soap. I

have found that a stannous sulfonate prepared from mahogany sulfonicacids may also be used satisfactorily in combination with'a phosphatidecompound -in 'the proportion ranges set forth above. The mahoganysulionic acids are the oilsoluble acids obtained from the treating ofminoral lubricating oil with sulfuric acid, and may be prepared andpurified'by conventional methods. The stannous soap of these acids'isprepared in a manner similar to the 'preparation of the stannousnaphthenate described above by first forming the alkali metal soap ofthese acids and then adding a solidstannous salt, such as stannouschloride, to efiect double decomposition and precipitation-of thestannous sulfonate. The resulting stannous sulfonate, preferablyemployed as a concentrate inmineral lubricating oil, is added to theDiesel lubricant in the manner set forth above for the stannousnaphthenate, and in combination with the above rnentioned proportions ofa; phosphatide; such as lecithin, imparts to the resulting and varnishdeposits. v

In order" to illustrate. the effectiveness of the compounded lubricantof the present invention in reducing oil ring sludge' in comparison withthe base oil, three runs were made on a so-called oil ring sludging testin aC. F. R. Diesel engine operating ioreacn runfor thirty-six hours at1200 R. P. M. with a jacket temp rature of 210 F. and a rich fuel'mixtureied atthe rate of 20 cc. per minute to thereby aggravate sludgeformation, the runs first being made on the blank oiland then on thesame oil containing '.5% stannous naphthenate and 5%, lecithin, andfinally on the blank oil. Thetotalweight ofsludge accumulating in theoil rings was weighed; and this sludge was extracted in each .instancewith 86" naphtha to separate the naphtha soluble portion or oil from theinsoluble portion 'rwhichjis The following results were obtained in the5 jacket-temperature being maintained at 375 F.

' The engine is equipped with a cast iron solidskirt piston withconventional piston rings; In prerun on aInaphthene-base S. A. E. '30oil com- 0.5% lecithin in comparison with the same base oil compoundedwith 1.3% of a previously known."

and approved Diesel oil additive, with respect to engine'oil-free sludgedeposits on the listed en'- gine parts. The run on the base oilcontaining 1.3% of said known additive was terminated at the end of 780.hours, and the weights of sludge deposit wereinterpolated to a 1000-hourbasis'for comparison;

I 7 Base oil+ I 0.6%stannous Base oil+ naphthen- 1.3% addiato+0.5five-:Wt lecithin-wt of deposit of deposit in grams in grams on ring 0.5f 259, Oilfilter 0.5 2.0 Under-side of piston 2.1 -12, 2 crankcase-""2.2 11.7

.As illustrative of the tfle ivenesioifmeats;

pounded oil of the present invention in reducing bearing corrosion, thefollowing empirical test was used. A special cadmium-silveror-copp'er-lead bushing which is .lined with the same alloy "as employedin rod bearings of automotive engines,

was-immersed in a. pot of the oil to bIe tested. which oil was heated toa contrvolled temperature of either 225 F. or 275? F. The oil iscontinuously circulated between the bushing and its journal by asuitable propeller or whirligig" for a. period of time varying from'tento forty hours. The bushing is weighed before the test and at tenhourintervals, and the loss in weightis listed in milligrams. The compoundedoil. of this .inve'ng; tion wascompared-with the same base oilcontaining a proportion of 1.3% of theabove-mentionedadditive which hadheretofore been la.pproved forthis service. The base oil used wasanaphthene-base S; A. E. 30 grade. The; followingresults wereobtained: i

BEARING c nde n-409mm AT 225 F.

"-10- 30x40 011 'Ihours "hours hours hours.

Baseoil+1%additive;-- s5 .350 50o. Base oil+1.3% additive 115 420 535595 Base oil+.5% stannous naph *thenate+.5%lecithin; 60 Base:oll+.5%.stannous naph-v v then ate-h5% le'clthin.. '65 100 210 BmnrnoCoaaosron-C mnm snv nr 27551.

7' 10 20- '30 40" 011 tested hours hours hours hoursBaseoil+l.3%additive 235" ass-p; Base oil+.5% stannous naph- I Hthcnate+.5 %le cithin. d 4 5 5 15 hours. i

' In addition to' the 1000-hour endurance-test mentioned above, thefollowing additional tests were run to'illus'trate the efiectiveness ofthe compounded oil of the present invention in reducing ring sticking.In this test,there was employed a single cylinder C. F. R. engineoperating -at 900 R. P. M. with a 5: 1 compression ratio, with 1 sparkadvance and wide open throttle, the

above-described 1000-hour Caterpillar entrance 4- paring" the engine fortesting. the rankcase, cylinder and piston are first cleaned thoroughlyto remove all depositsand to provide a perfectly clean engine The engineis then reassembled Heretofore these polyvalent metal soaps havelubricating oil additives because of their limited solubility in variousbase oils and their instability and the crank case charged with therequired 5 in operation and in storage. It has been found amount of.oil, generally 3000 'cc. The engine is i that these metal soaps, eventhough soluble in a then operated to give maximum power under theparticular base oil, are very apt to separate from conditions set forthabove for a period of time, the oil even on short term storage. Since itis generally eighteen hours. The oilis drained imvery seldom that afreshly compounded oil is mediately after stopping, the engine allowedto I0 immediately put into use, the oil must be sufllcool for at leastthree hours, and then the cylinder ciently stable to withstand storage,either light or removed and the piston rings inspected. If the dark, ofupward of one month.

rings are found free, the cylinder and oil replaced Another factor whichhas been found prevalent and the run continued for an additionaleighteen among th polyvalent metal soaps is their limited hours,when-itis again disassembled and insolubility in the various base oils.For example, spected. This procedure is continued until sticl a metalsoap may be sufliciently soluble in a ing occurs, generally'of the toppiston ring, or naphthene base oil to be used advantageously until therun has continued for such a length of therewith and still becomparatively insoluble in time as to be conclusive without actualsticking. either a parafiin base oil or a paraflln naphthene If, at anyinspection, rings are on the verge of blend oil. With the addition ofsmall proportions sticking, the additional run may be reduced to of aphosphatide to these metal soaps, their solutwelve hoursor less. When asevere ring sticking bility in a hydrocarbon oil has been increased andcondition is observed, the sticking time is estithe resulting lubricantfound to be stable for long mated at some time between that of the finaland periods of storage. the preceding inspection. An accuracy of six vAmong the polyvalent metal soaps which are hours is generally obtained.The following are affected by the addition of a phosphatide are the theresults of runs made on an airplane oil, which polyvalent metal soaps offatty acids, modified is a solvent-refined residual paraffin-baselubrifatty acids, sulfonic acids, and naphthenic acids. eating oilhaving a S. U. viscosity at 210 F. of These heavy metal soaps may be thealuminum.

- about 120, and on the same oil compounded with barium, calcium,cadmium, strontium, mercury, 5% stannous naphthenate and 5% lecithin:iron, zinc, copper, cobalt, nickel, manganese, magnesium, tin and leadsalts of saturated or unsat- Ring urated fatty acids obtained from fats,oils, resins on tested and waxes, or substituted derivatives thereofconmm taining halogen, sulfur and nitrogen substituents.

I together with their alkyl and aralkyl derivatives. Base airplane oilThe p osphatide compound iS added 130 the Base oil 0.5% stannousnaphthenate 0.5% lecithin... 70 to il i a proportion range of f 0 1 2 0%by weight, and when used in combination with the In preparing aconcentrate of both additives, it 40 above-mentioned polyvalent metalsoaps the preis preferable to firstcharge the mineral lubricatferredproportion range is dependent upon the in il. such s a n p a f aviscosity f particular soap and the particular base oil to 300 at 100F., heat-to about 150 F., add the 'stanwhich it is added, For example,in preparing a nous'naphthenate and mechanically stir until dis- Diesellubricant with a combination of calcium solved. The lecithin is thencharged W ile. t e 5 dichlor stearate and lecithin, the preferred rangetemperature is maintained at about 150 F. or in a paraffin base oil is0.13.0% by weight of cali h y b l and again a ly stirred cium dichlorstearate'with 0.5-1;25% by weight of until a homogeneous solution isobtained. A very lecithin. When using the above preferred prosuitableconcentrate of this character is one conportion range of calcium dichlorstearate in a taining by weight about 25% stannous naph- 5onaphthene-paraffin blend oil with a 1:1 ratio, the thenate, 25% lecithinand Oil. However. the preferred proportion range of lecithin is betweenconcentrate can be prepared to contain the addi 0.1% and 1.0%, and foranaphthene base oil tiveszin either greater or lesser proportions thancontaining the same percentage of calcium dithose specified, butpreferably to contain about chlor stearate the preferred proportion oflecithin 20-70% of total additives. is in a range between 0.1 to 0.75%.

I have further discoveredthat when small pro- In order to exemplify theeffect of th 1 portions of a phosphatide, such as lecithin, are phati deof th present invention on a polyadded to a p ly metal oap additive andvalent metal soap with regard to its solubility compounded in1ubricating oil. the pho phatide in a hydrocarbon oil and the resultingstability improves the ing haracte stics of the on storage, thefollowing data were obtained, metal soaps andrenders the compounded 011EX using calcium dichlor steal-ate as the metal soap tremely stable inboth operation and'storage. with various base oils:

. Calcium Appearance of sample aiter- Base oil dichlor LecithinSte/Prat? 'lwo months Five months I .Per cent Per centNaphthene+paraifin (11) S A E 30-... 2.5' None Definite separation ofadditive Definite separation of additive. D 2. 5 O. 1 Clear; no haze orseparation of additive.... Slight haze in oil.

Naphthen 4.44 None Precipitate Do.- 4. 44 Clear; no haze or separationof additive Very slight haze. 130.-

3.25 .-...do Do 3.25

, varying from two to ten hours.

As an example of th effect of the phosphatide on the inhibitingproperties of the metal soap, the following empirical corrosiontest wasmade, using calcium dichlorstearate as the corrosion inhibitor. In thistest a copper-lead bearing specimen, incased in a special-non-wearbushing and rotatably mounted on a stainless steel shaft, was immersedin a glass pot of the oil to be tested. The tested oil was heated to acontrolled temperatur of ither 250 F. or 350 F. and continuouslycirculatedbetween the bearing specimen and the shaft for periods of timeThe bearing specimen was weighed before the test and at the end of theten hour period and the loss in weight recorded in milligrams. The baseoil used was a naphthene base S. A. E. 30 grade. The results of two runsat 250 F. and 350 F. respectively, are presented:

BEARING CORROSION--COPPER LEAD Hones) Weight loss in mgs.

Oil tested 250 F. 350 F.

Base oil 4.44% calcium dichlor stearate Base oil 4.44% calcium dichlorstearete 0.2% lecithin i.

6. The method of lubricating the bearings and cylinders of a Dieselengine which comprises supplying to the bearings and cylinders of suchengine a naphthene base mineral distillate lubrieating oil within themotor oil viscosity range containing about 0.1-0.5% of lecithin andabout 0.5-1.5% of a stannous soap selected from the groupeonsistingwi'stannous naphthenate and stannous sulfonate.

7. The method of preparing a motor oil adapted for the lubrication ofthe bearings and cylinders of an internal combustion engine, whichcomprises adding a. stannous soap selected from the group consisting ofstannous naphthenate and stannous sulfonate to a mineral lubricating oilat an elevated temperature of about 150 F. and below, mechanicallyagitating to form a group consisting of stannous naphthenat and rstannous sulfonate. 1

2. A Diesel lubricating oil adapted for crank case lubrication of 9.Diesel engine comprising a naphthene base lubricating oil'within themotor oil viscosity range containing about 0.1-2.0% by weight oflecithin and about 0.1-2.0%- by weight of stannous naphthenate.

3. A Diesel lubricating oil adapted for crank case lubrication of aDiesel engine comprislnga naphthene base lubricating oil within themotor oil viscosity range containing about 0.1-2 .0% by weight oflecithin and about 0.1-2.0% by weight of stannous sulfonate.

4. A Diesel lubricating oil adapted for crank case lubrication of aDiesel engine comprising a naphthene base mineral distillate lubricatingoil within the motor oil viscosity range containing about 0.5% by weightof lecithin and about 0.5% by weight of a stannous soap selected fromthe group consisting of stannous naphthenate and stannous sulfonate.

5. The method of lubricating the bearings and cylinders of an internalcombustion engine which comprises supply ng to the bearings andcylinders of such engine a mineral lubricating oil within the motor oilviscosity range containing 0.1-2.0% by weight of a phosphatide compoundand about 0.1-2.0% of a stannous soap selected from the group consistingof stannous naphthenat and stannous sulfonate, the oil being effectivein reducing ring sticking and bearing corrosion and inhibiting varnishformation and oil ring sludge deposits.

solution, adding a phosphatide to said solution at said elevatedtemperature and mechanically agitating to form a homogeneous solution inthe form of a mineral lubricating oil concentrate,

and then adding the concentrate to the bulk of the mineral lubricatingoil of motor oil viscosity range in a proportion to give by weight about01-20% of the phosphatide and 0.1-2.0% of the stannous soap therein. I

8. A lubricant comprising a mineral lubricating oil, a stannous soap andabout 0.1-2.0% by weight of lecithin.

9. A lubricant comprising a lubricating oil', a, metal salt of acarboxylic acid in'an amount in excess of that which would be soluble insaid lubricating oil and a phosphatidic material in an amount suflicientto render said first mentioned amount of said salt soluble in said oil.

10. A lubricant as claimed in claim 9 wherein the phosphatidic materialcomprises lecithin and cephalin.

11. A lubricant as claimed in claim 9 wherein the phosphatidic materialcomprises cephalin.

12. A lubricant as claimed in claim 9 wherein the phosphatidic materialcomprises lecithin.

'13. A lubricant comprising a lubricating oil, a. metal salt of analiphatic acid in an amount in excess of that which would be normallysoluble in said lubricating oil. and a phosphatidic material in anamount suflicient to render said firstmentioned amount of metal saltsoluble in said oil.

14. A lubricant comprising a lubricating oil, a group II metal salt ofan aliphatic acid in an amount in excess of that which would be normallysoluble in said lubricating oil, and a phosphatidic material in anamount suillcient to render said first-mentioned amount of metal saltsoluble in said oil.

15. A process for improving a. lubricating oil comprising incorporatingwith said 011 a metal salt of an aliphatic acid in an amount in excessof that which would be normally soluble in said lubricating oil, and aphoslihatide in an amount sufficient to render said flrst mentionedamount of salt soluble in said oil.

16.- A process for improving a lubricating oil comprising incorporatingwith said oil an alkaline earth metal stearate in an amount in excess ofthat which would be normally soluble in said lubricating oil. and aphosphatltle in an amount suflicient to render said first-mentionedamount of salt soluble in said oil.

1'7. A lubricant comprising a lubricating oil, a polyvalentmetal soap inan amount in excess of that which would be normally soluble in saidlubricating oil, and a phosphatidic material in

